Calathea care: humidity, water quality and steady warmth

Light

Calatheas evolved on the shaded forest floor, and their thin, patterned leaves bleach in strong sun. NC State recommends indirect, medium light, about 150 foot-candles in University of Illinois Extension terms, which you find directly in front of a north window or a few feet from an east or west one. The RHS suggests a north- or east-facing window in summer, then a move to a south-facing sill in winter, when the sun is weaker and lower.

Watch the markings. Faded patterns are NC State's sign of insufficient light, and the RHS warns that Goeppertia species in particular make poor, weak growth when it is too dark; a grow light fixes a gloomy room. At the other extreme, direct sun scorches the leaves, so bright light should always arrive filtered.

Water

Keep the mix evenly moist from spring through summer, never soggy and never bone dry. NC State asks for soil that stays consistently moist but not wet, and the RHS describes moderate watering that keeps the compost evenly damp. In practice that means watering as soon as the surface loses its dark, damp look, then emptying the cover pot, since the RHS warns that roots left standing in water rot quickly.

Winter changes the rhythm. The RHS advises letting the surface dry before rewetting in autumn and winter, without ever letting the compost dry out completely, and warns that a winter pot kept too wet brings oedema, patchy water-soaked areas on the leaves. NC State's rattlesnake plant page likewise says to cut back watering when growth slows.

What you pour matters as much as when. NC State recommends distilled water or rainwater because the fluoride in tap water browns leaf tips and edges. The RHS says calatheas will tolerate tap water left to stand for at least 24 hours so the chlorine can evaporate. Clemson Extension adds two rules for all houseplants that calatheas take seriously: never use softened water, which adds sodium and chloride, and keep the water between 62 and 72°F. Aim at the soil, not the leaves; NC State links wet foliage to leaf spot.

Soil and pH

NC State calls for a rich, moist, well-drained potting mix high in organic matter, with perlite added for drainage, and its species pages describe slightly acidic to neutral soil. The RHS recipe is simple: a peat-free multipurpose or houseplant compost with about 10 percent potting grit by volume, free-draining yet moisture-retentive. Skip cactus mix, which dries too fast for a plant that should never go fully dry, and never use garden soil, which packs down and stays waterlogged in a pot.

Humidity

Humidity is the make-or-break factor. NC State's pages for orbifolia and the peacock plant set a target of at least 60 percent relative humidity, while the University of Illinois Extension notes that most homes fall below 30 percent in winter. Crisp brown leaf edges are the predictable result. A humidifier is the most reliable fix; a tray of wet pebbles, a cluster of plants, or a bright bathroom or kitchen, all suggested by NC State and the RHS, help as well.

Temperature

NC State gives 65 to 75°F for the genus, and the RHS a slightly cooler 61 to 70°F (16 to 21°C). Both stress steadiness over any exact number: avoid drafts, sudden swings and direct heat from radiators. The RHS adds that calatheas are easily damaged by cold, so wrap a new plant well when carrying it home in winter. NC State lists cold exposure, together with overwatering, as a cause of rotting stems and drooping leaves.

Fertilizer

Feed lightly and only while the plant grows. NC State recommends a half-strength houseplant fertilizer during the growing season, and both its species pages and the RHS suggest feeding monthly, the RHS from April to September with a balanced or general-purpose liquid feed. Stop in autumn and winter. The RHS also notes that slow-release fertilizer mixed in at repotting means no liquid feed is needed for the first year. The University of Illinois Extension warns that too much fertilizer can burn roots, so when in doubt, feed less and flush the pot with rainwater now and then.

Work out the dose for your watering can with the fertilizer dilution calculator →

Repotting

NC State suggests repotting every year or two, preferably in spring, while the RHS says every few years once the clump has filled the pot, in spring or summer. Newly bought plants can usually stay in their nursery pot for the first growing season, according to the RHS. When you do move one, go up only one or two pot sizes and set the top of the root ball just below the surface of the new mix. Repotting is also the natural moment to divide an overcrowded clump.

• The clump of stems fills the pot from rim to rim
• Roots push out of the drainage holes
• The mix dries much faster than it used to

Propagation

Division is the propagation method NC State gives for Goeppertia. In spring, slide the clump out, find the natural breaks between groups of stems, and cut through the rhizome so each section keeps several leaves and its own roots, as the RHS describes. Pot each piece and keep it warm, humid and moist until it grows again; a clear plastic bag over the pot helps. NC State's peacock plant page suggests dividing every two years to keep plants vigorous. Stem cuttings are an option only for branching relatives such as Ctenanthe, the RHS notes.

Methods: Division of the rhizomatous clump · Best season: spring.

Common problems

Calathea symptoms are unusually specific. Brown tips and edges usually mean dry air or fluoride and chlorine in the water. Leaves that roll inward are underwatered, NC State says, and yellowing can come from either too little or too much water. Drooping stems that rot at the base follow cold and wet together. Faded patterns mean too little light, scorched patches too much, and patchy water-soaked spots in winter are oedema from a pot kept too wet. According to the RHS, spider mites leave speckled, yellowing leaves and fine webbing, while mealybugs or soft scale leave black sooty mold behind.

Not sure which one it is? Try the plant problem diagnosis tool →

Is the calathea toxic to cats and dogs?

Good news for pet owners: the ASPCA lists Calathea (Calathea spp.) as non-toxic to cats, dogs and horses, and also lists the prayer plant, under the scientific name Calathea insignis, as non-toxic. That makes calatheas one of the safer foliage choices for a home with a cat that chews leaves. Non-toxic does not mean meant to be eaten, though, and a pot recently treated with insecticide or fertilizer brings its own risks. Call your veterinarian if a pet eats a large amount of any plant or seems unwell afterward.

Check any other plant against the ASPCA lists →